---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Tue 12/27/05: 12 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:48 AM - Re: Manual Battery Switches. (Eric M. Jones) 2. 07:45 AM - Re: Re: Choosing a switch and learn how to wire it (Carlos Trigo) 3. 07:56 AM - Switch/Relay Contact Ratings (Tim Olson) 4. 08:34 AM - Manual Battery Switches (rd2@evenlink.com) 5. 08:42 AM - Re: Re: Manual Battery Switches. (Jerry Grimmonpre) 6. 09:26 AM - Re: Switch/Relay Contact Ratings (Robert L. Nuckolls, III) 7. 09:34 AM - Re: Re: Choosing a switch and learn how to (Robert L. Nuckolls, III) 8. 01:41 PM - Re: Manual Battery Switches. (Eric M. Jones) 9. 02:05 PM - Requesting Peer Review of Electrical Architecture () 10. 04:10 PM - Re: Choosing a switch and learn how to wire it (Speedy11@aol.com) 11. 06:09 PM - Re: Choosing a switch and learn how to wire it (Bill Schlatterer) 12. 07:35 PM - Re: Re: Manual Battery Switches. (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 06:48:45 AM PST US From: "Eric M. Jones" Subject: AeroElectric-List: Re: Manual Battery Switches. --> AeroElectric-List message posted by: "Eric M. Jones" I am convinced that an electric battery contactor is unnecessary for my system. I have steered other builders to "Flaming River" remote battery switches. These are racecar switches and should fit in RV's just fine, but rolling your own is easy to do if you use the basic parts from a cheap battery switch. Harbor Freight 91477-0VGA or even 33783-0VGA or similar. I have planned to put the parts into a battery case as shown with the big shunt and the Xantrex XBM battery monitor. The fuses shown are from the XBM installation manual. They may disappear when I examine what they do. http://www.periheliondesign.com/BatteryMechanicalSchematic.jpg or http://www.periheliondesign.com/BatteryMechanicalSchematic.dxf Notice that the "EMERGENCY" T-handle also shuts off the fuel and does other things to simplify the "Crash" checklist. Also please note that automobiles do not have B+ disconnects, but the emergency personnel carry a big set of cable shears and that's the first tool they use when arriving on the scene. Regards, Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge MA 01550-2705 (508) 764-2072 "Democracy is the theory that the common people know what they want and deserve to get it good and hard." -- H. L. Mencken ________________________________ Message 2 _____________________________________ Time: 07:45:03 AM PST US From: "Carlos Trigo" Subject: Re: AeroElectric-List: Re: Choosing a switch and learn how to wire it --> AeroElectric-List message posted by: "Carlos Trigo" > --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" > > What does the manufacturer suggest? > Can you send me wiring diagrams? Are installation instructions > downloadable from their website? See http://www.grtavionics.com/documents/EFIS%20Series%20I%20Installation%20Manual%20010405.pdf specially pages 3 and 4 and http://www.grtavionics.com/documents/Display%20Unit%20Connector%20Definitions%20Rev%20D.pdf and http://www.grtavionics.com/documents/AHRS%20and%20Magnetometer%20Pinout.pdf > How does your load analysis stack up that you would > find yourself in a "save power" mode? These devices > use so little energy that I would think you can easily > craft an endurance mode that would make shutting the > EFIS off unnecessary. I think I can agree with you. I'm going to confirm my load analysis. > If there are no EFIS controls for independent control of > activity and you believe there is value in shutting the system > off, then a switch becomes necessary. I'd like to understand > the imperative for ever shutting it off. We don't do it > on any of our glass-cockpits at RAC. Well, I didn't know that. I confess that I've never flown with a glass cockpit, therefore I've no experience. I thought it would be good to be able to shut the EFIS Off, keeping other avionics On. Maybe I can change my mind. Nevertheless, please review above links to GRT avionics and give me your opinion Thanks Carlos ________________________________ Message 3 _____________________________________ Time: 07:56:58 AM PST US From: Tim Olson Subject: AeroElectric-List: Switch/Relay Contact Ratings --> AeroElectric-List message posted by: Tim Olson I've got a question that's concerning me about relay contact ratings. I have the B&C S704-1 20A relay. It's a Potter & Brumfield T9AP5D52-12 with the following ratings: NO NC=10 240 VAC Now I thought that since this is a recommended product for 20A service, that I could trust that, but when looking at the ratings, it's showing 20A@240VAC. From everything I thought I ever learned about switches, the AC rating is no big deal... the DC rating is the hard one to pass and is usually much lower, correct?. So what's this relay REALLY going to be good for in DC service? Tim -- Tim Olson -- RV-10 #40170 DO NOT ARCHIVE ________________________________ Message 4 _____________________________________ Time: 08:34:37 AM PST US From: rd2@evenlink.com Subject: AeroElectric-List: Manual Battery Switches --> AeroElectric-List message posted by: rd2@evenlink.com Eric, 33783-0VGA is 100 amps continuous, 1000 amps surge @ 12 volt; 50 amp continuous, 500 amps surge @ 24 volt; 33783-0VGA - no current data provided Just wondering - would these be ok for cranking also? Rumen _____________________Original message __________________________ (received from Eric M. Jones; Date: 09:44 AM 12/27/2005 -0500) --> AeroElectric-List message posted by: "Eric M. Jones" I am convinced that an electric battery contactor is unnecessary for my system. I have steered other builders to "Flaming River" remote battery switches. These are racecar switches and should fit in RV's just fine, but rolling your own is easy to do if you use the basic parts from a cheap battery switch. Harbor Freight 91477-0VGA or even 33783-0VGA or similar. ----snip----- ________________________________ Message 5 _____________________________________ Time: 08:42:01 AM PST US From: "Jerry Grimmonpre" Subject: Re: AeroElectric-List: Re: Manual Battery Switches. --> AeroElectric-List message posted by: "Jerry Grimmonpre" Eric ... also at harbor freight http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=92688 is the identical manual batt sw, w/o the funky moisture cap, for the "blue light" sale price of only $5.99 reached through search # 92688-0VGA. I like the Flaming River batt disconnect better, it's push-pull but a bit pricey. Jerry Grimmonpre' Subject: AeroElectric-List: Re: Manual Battery Switches. > --> AeroElectric-List message posted by: "Eric M. Jones" > > > I am convinced that an electric battery contactor is unnecessary for my > system. I have steered other builders to "Flaming River" remote battery > switches. These are racecar switches and should fit in RV's just fine, but > rolling your own is easy to do if you use the basic parts from a cheap > battery switch. Harbor Freight 91477-0VGA or even 33783-0VGA or similar. > Regards, > Eric M. Jones > www.PerihelionDesign.com ________________________________ Message 6 _____________________________________ Time: 09:26:40 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Switch/Relay Contact Ratings --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 09:56 AM 12/27/2005 -0600, you wrote: >--> AeroElectric-List message posted by: Tim Olson > >I've got a question that's concerning me about relay contact >ratings. > >I have the B&C S704-1 20A relay. > >It's a Potter & Brumfield T9AP5D52-12 >with the following ratings: >NO >NC=10 >240 VAC > > >Now I thought that since this is a recommended product for 20A >service, that I could trust that, but when looking at the >ratings, it's showing 20A@240VAC. From everything I thought I >ever learned about switches, the AC rating is no big deal... >the DC rating is the hard one to pass and is usually much >lower, correct?. So what's this relay REALLY going to >be good for in DC service? See: http://www.aeroelectric.com/articles/swtchrat.pdf Switch (and relay) ratings have to do with arcing control which is easier in AC than DC. Keep in mind that ratings have to do with contact performance AFTER some number of switching cycles that range from 10,000 to 100,000 depending on how ambitious and adventuresome the manufacturer. If you flew every day, it would take you years to put 1/10th the ratings value for wear and tear on a switch or relay. Here's a contactor that's used well inside it's published ratings but we still see a couple failures a year out of a fleet of 7,000 aircraft. http://www.aeroelectric.com/Pictures/Contactors/6041_Contactor.jpg http://www.aeroelectric.com/Pictures/Failures/6041_Contactor_Failure.jpg This contactor sees a 100A continuous load (rated for 200) on the air-conditioner drive motor. On the other hand, here's another failed relay contact: http://www.aeroelectric.com/Pictures/Failures/HiRes1.jpg http://www.aeroelectric.com/Pictures/Failures/HiRes2.jpg This contact is OPEN circuit . . . didn't have enough current flowing in it to keep the contacts clean. None-the-less, operated well inside its ratings. Here's a a contact pair that sticks occasionally. Again, operated well inside its ratings: http://www.aeroelectric.com/Pictures/Failures/1_B30K3_stick.jpg http://www.aeroelectric.com/Pictures/Failures/Stick_1.jpg http://www.aeroelectric.com/Pictures/Failures/Stick_2.jpg Most of the failures above operated more flight hours than you'll ever put on your airplane. All of the failures were in circuits where the designer dutifully accommodated the manufacturer's ratings for the device. Some of those pictures were taken in the course of deducing some VERY expensive failures in terms of time to trouble shoot and downtime on revenue generating machines. But at the same time, they represent less than 1/100th of 1% of all potential contact failures in a given fleet. Don't agonize over it. We worry about those things in certified and military aircraft because we have to test to endurance ratings that match what we claim for our products. But in the final analysis, very few moving contact devices get trashed because of unreasonable operating stresses. Bob . . . ________________________________ Message 7 _____________________________________ Time: 09:34:54 AM PST US From: "Robert L. Nuckolls, III" wire it Subject: Re: AeroElectric-List: Re: Choosing a switch and learn how to wire it --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" wire it > > What does the manufacturer suggest? > > Can you send me wiring diagrams? Are installation instructions > > downloadable from their website? > >See >http://www.grtavionics.com/documents/EFIS%20Series%20I%20Installation%20Manual%20010405.pdf > >specially pages 3 and 4 > >and >http://www.grtavionics.com/documents/Display%20Unit%20Connector%20Definitions%20Rev%20D.pdf > >and >http://www.grtavionics.com/documents/AHRS%20and%20Magnetometer%20Pinout.pdf > > > > > If there are no EFIS controls for independent control of > > activity and you believe there is value in shutting the system > > off, then a switch becomes necessary. I'd like to understand > > the imperative for ever shutting it off. We don't do it > > on any of our glass-cockpits at RAC. > >Well, I didn't know that. I confess that I've never flown with a glass >cockpit, therefore I've no experience. I thought it would be good to be able >to shut the EFIS Off, keeping other avionics On. Maybe I can change my mind. >Nevertheless, please review above links to GRT avionics and give me your >opinion This is a REALLY disappointing set of instructions. Not one schematic. The functionality of a pin in a connector and the best places to hook it are best described in schematics. I once spent two weeks in Compton CA teaching Japanese technicians how to troubleshoot and align some video equipment we manufactured. They spoke very little English, I spoke zero Japanese but we both knew television signal processing and schematics were the universal language for deducing functionality of the system. We managed rather well. Had I published manuals like those cited above, well . . . I'll read these and see if I can deduce from the language and vernacular EXACTLY what the writer intends for you and me to understand. Bob . . . ________________________________ Message 8 _____________________________________ Time: 01:41:36 PM PST US From: "Eric M. Jones" Subject: AeroElectric-List: Re: Manual Battery Switches. --> AeroElectric-List message posted by: "Eric M. Jones" --> AeroElectric-List message posted by: rd2@evenlink.com >Eric, >33783-0VGA is 100 amps continuous, 1000 amps surge @ 12 volt; 50 amp >continuous, 500 amps surge @ 24 volt; 33783-0VGA - no current data provided >Just wondering - would these be ok for cranking also? Rumen Rumen, That's a definite maybe. I don't know how these specs were designed. But the connector only has to open under load once, and they use these things on vehicles routinely. I'd make sure they were silicone greased too. Regards, Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge MA 01550-2705 (508) 764-2072 "Democracy is the theory that the common people know what they want and deserve to get it good and hard." -- H. L. Mencken ________________________________ Message 9 _____________________________________ Time: 02:05:43 PM PST US From: Subject: AeroElectric-List: Requesting Peer Review of Electrical Architecture INNOCENT GLOBAL 0.3422 1.0000 -0.1809 --> AeroElectric-List message posted by: Responding to an AeroElectric-List message previously posted by: Kevin Horton 12/27/2005 Hello Kevin, Thanks for your input. <<1) You wrote: "But, this should only occur following an electrical failure.">> Right you are. <<2) You wrote: "If we have to comply with all the FARs following a systems failure,...skip...>> My concern was not with the routine compliance with FAR's following a systems failure. My concern was Jeff being in IMC, with an alternator failure, depending upon battery reserve, being vectored by ATC to a nearby safe letdown destination with terrain clearance a factor, and Jeff's transponder not transmitting altitude information because his encoder was not on the endurance bus. Since 14 CFR Sec. 91.215 specifically requires a transponder to be putting out altitude information that reference seemed to be the most succinct wording to describe the altitude reporting requirement. Jeff's email response to me was that he was moving his altitude encoder to the endurance bus. OC < bus only (altitude encoder not functioning) that you will not be in > compliance with 14 CFR Sec. 91.215. Do you concur? Is this of concern to > you?>> <> ________________________________ Message 10 ____________________________________ Time: 04:10:49 PM PST US From: Speedy11@aol.com Subject: AeroElectric-List: Re: Choosing a switch and learn how to wire it --> AeroElectric-List message posted by: Speedy11@aol.com In a message dated 12/27/05 2:59:00 AM Eastern Standard Time, aeroelectric-list-digest@matronics.com writes: Good Morning Stan, I agree, but don't you think my solution would work as well? I always thought simpler was better! Yes Sir. Stan Do Not Archive ________________________________ Message 11 ____________________________________ Time: 06:09:22 PM PST US From: "Bill Schlatterer" Subject: RE: AeroElectric-List: Choosing a switch and learn how to wire it --> AeroElectric-List message posted by: "Bill Schlatterer" Carlos, I know you have thought this out and I assume this is the GRT unit but have you considered that the EFIS chooses which bus has the higher voltage automatically. If you go with ON-OFF-ON you will cause a reboot as you switch through power sources and actually defeat the purpose of the multiple power source availability. If you switch both sources to the EFIS so that both are on at the same time, the EFIS will draw off the higher bus. Todd says the system will not allow one bus to drain the other. Assuming that to be true, you may not really gain anything from the On-Off-On set up. Can't remember the switch number but there is one that switches both power sources to the EFIS independently in a simple On-Off mode and then lets the EFIS pick whichever has the higher voltage. Even simpler, I "think" you could accomplish the same thing with a diode in each power feed to a simple on/off toggle. In my configuration, I have a separate switch for the DUs and AHRS but each switch applies two power sources to the unit and lets it do the rest. This is all new to me also so if I am missing the obvious please feel free to says so, Thanks Bill S 7a Dual GRT fuse/panel -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com]On Behalf Of Carlos Trigo Subject: AeroElectric-List: Choosing a switch and learn how to wire it --> AeroElectric-List message posted by: "Carlos Trigo" First of all I must say I'm not an EE and as you're going to confirm, I'm far away from being a DC expert. The only good thing I'm near is that I'm humble enough to admit my ignorance and I like to learn ..:-). Well, for the experts, my problem certainly is a simple task. I am wiring my EFIS and need to figure out a switch to control power to both devices, the Display Unit and the AHRS. Both have D-Sub connectors that allow 3 alternative power sources, from wich I intend to use 2. So, I want to connect power from 2 diferent buses to the 2 separate units, and do it through a 3 positon switch (On-Off-On). For better understanding of my "problem", what I want is a switch that has 1 OFF position (no power for both EFIS units), 1 ON position (power from one source bus is feeding both units) and other ON position (power from 2nd source bus is feeding both units). Which kind of switch do I need, and how is wiring done? Thanks in advance Carlos ________________________________ Message 12 ____________________________________ Time: 07:35:41 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Manual Battery Switches. --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" > > >33783-0VGA is 100 amps continuous, 1000 amps surge @ 12 volt; 50 amp >continuous, 500 amps surge @ 24 volt; 33783-0VGA - no current data provided >Just wondering - would these be ok for cranking also? Rumen Again, a good example of what switch ratings mean and what they often fail to explain. Switches are rated to do SWITCHING. Their service life is likely to be achieved if one does not exceed limits while SWITCHING. Keep in mind that a battery contactor generally SWITCHES relatively small loads assuming most things are OFF when the master switch is closed . . . well under 20A. Now, when you hit the starter button, a starter contactor does the switching but impresses the starter motor's inrush currents on all other components in the system including the battery contactor. The widely used RBM/Stancore/White-Rogers contactors are rated to SWITCH only 70A yet once the contacts are closed and stable, they don't mind the 500+ amp inrush it takes to spin up a starter motor from a healthy battery. The battery switches under discussion are equally suited to cranking engines as long as you're not using the battery switch to CONTROL the starter . . . this is the job of another, intermittent duty contactor designed for that service. Bob . . .